Patients with Lynch carry an increased risk for certain cancers, such as colorectal, endometrial, ovarian, stomach, and more.

Early-age onset colorectal cancer is a flag for Lynch syndrome, and young patients should be tested.

Unfortunately, an estimated 95% of Lynch syndrome cases are undiagnosed.

The Lynch syndrome genes are in a class of genes called mismatch repair (MMR). MMR genes work like “spell checkers.” Every time your body needs to make a new cell (which happens frequently), it makes an exact copy of your genetic material. The MMR genes “spell check” the new copy of DNA to identify any mistakes that were made while it was being copied, and then the genes repair those mistakes.

If the MMR genes are mutated and not working properly, these mistakes cannot be repaired, and the new cells will have an abnormal copy of its genetic material. This is known as MMR-deficient, or MMR-D.

Muir-Torre syndrome is an older term used to describe families with Lynch syndrome who have certain types of Lynch syndrome-related skin growths and cancers.

Turcot syndrome is an older term used to describe families with Lynch syndrome who have brain tumors (usually glioblastomas).

It is now known that anyone with Lynch syndrome can develop these skin growths/cancers and brain tumors so these names are not being used anymore.

As many as 1 in every 300 people may be carriers of a change, also called an alteration or mutation, in a gene associated with Lynch syndrome. Around 3 out of 100 people with colorectal cancer have Lynch syndrome.

How and when you get tested for Lynch syndrome will depend on if you have or have not been diagnosed with cancer.

Many institutions now perform a screening test on all colorectal cancers and endometrial (uterine) tumors at the time of surgery. If you’re not sure if this test was done, ask your oncologist. If your surgery was not too long ago, it’s likely the test can still be performed if it wasn’t done.

Most hospitals do one of these two screening tests, if not both:

If you have not been diagnosed with cancer, ask your biological family members who have cancer about their genetic testing results. This may influence your next steps. It’s important to work with a genetic counselor who can help you understand the process.

Your biological family history may give you clues that Lynch syndrome runs in your family and you would benefit from getting tested:

• There are multiple generations on one side of the family (great-grandparent, grandparent, parent, aunt/uncle, child) with a Lynch-associated cancer
• There may be “clustering” of Lynch-associated cancers in the family
• Individuals in the family may have more than one cancer
• Individuals may be diagnosed with cancer at younger ages than average

Many insurance plans and some genetic test providers will offer genetic testing if there’s been a diagnosis of Lynch syndrome in the family. It’s important to speak with a genetic counselor about your testing options.

To find a genetic counselor knowledgeable about hereditary gastrointestinal cancer, search the CGA-IGC map.

Genetic testing can be beneficial for both the cancer patients and their biological family members. Patients should have their tumors tested following surgery, however, a follow-up with a genetic counselor is advised for both the patient and any family members. These follow-up visits often collect blood or saliva and use these samples for genetic testing.

Talk with your genetic counselor to form a game plan for your unique case and make sure you understand which genes are being tested. In some cases, depending on your health and your family member’s health, you may be tested for one gene, or a handful of genes. In other cases, a full panel may be run.

A genetic counselor can advise what type of testing you need, and how frequently.

In general, people tested prior to 2013 may need updated testing since that is when panel testing first became available (testing for multiple genes at one time).

Although 23andMe has brought some awareness to hereditary colorectal cancer, it does not offer any tests that look at the Lynch syndrome genes. The 23andMe test looks at two common mutations in the MUYTH gene (not the entire gene), which is associated with a recessive condition (this means you have to have two mutations, one from each parent, to be affected) that causes colorectal polyps and cancer.

Currently 23andMe, along with other direct consumer testing options, could give a person a false sense of their overall colorectal cancer risk due to hereditary colorectal polyps/cancer genes.

Although it’s uncommon, it is possible to carry a Lynch syndrome gene mutation and not have a family history. In these cases, the patient with Lynch is considered “de novo,” or the first in the family line to carry the mutation.

Your first-degree blood relatives (mother, father, adult siblings and children) should be tested for Lynch syndrome if you are positive. Most people diagnosed with Lynch syndrome inherited the mutation from one of their parents, and each of their children carry a 50% chance of also inheriting the mutation.

The diagnosis of a genetic syndrome can be scary, but knowledge is power! The sooner you know if you carry a Lynch syndrome gene, the more aggressive you can be to prevent cancer.

Not everyone who is diagnosed with Lynch syndrome will get cancer, but everyone with Lynch syndrome carries a higher risk for certain cancers.

“Previvor” is the term that describes someone with Lynch syndrome who has NOT been diagnosed with cancer. If you have Lynch syndrome, it is critical to notify all of your doctors so you can follow an aggressive cancer screening and prevention plan.

Lynch syndrome itself doesn’t come with any symptoms; but the cancers associated come with a variety of symptoms. Make sure you know the symptoms of colorectal cancer, as well as symptoms of other cancers like ovarian and endometrial. Knowing your family’s health history is important because you can pay extra attention to your body for any symptoms that may be associated with Lynch cancers.

The NCCN recommends these general screening and risk-reduction guidelines for Lynch syndrome patients:

Colonoscopy: For individuals with an MLH1 or MSH2 mutation, every one to two years beginning between the ages of 20 to 25, or five years younger than the earliest age at diagnosis in the family (whichever is sooner). For individuals with an MSH6 or PMS2 mutation, every one to three years beginning between the ages of 30 to 35, or five years younger than the earliest age at diagnosis in the family (whichever is sooner).

Upper endoscopy: Every two to four years starting at age 30-40, in addition to testing for Helicobacter pylori infection at a baseline exam with treatment if positive

Total body skin examination: Yearly

Pelvic examination/pelvic ultrasound/endometrial biopsy (women): Every 1-2 years from age 30 to 35 (up until the time of a hysterectomy/oophorectomy)

Taking a daily aspirin, which may be linked to a reduced risk of colorectal cancer and possibly other cancers in individuals with Lynch syndrome. Before taking aspirin, discuss with your doctor.

You should talk to your doctor for more tailored screening recommendations based on your personal and family history.

Hereditary nonpolyposis colorectal cancer, or HNPCC, is often called Lynch syndrome. Although the two hereditary conditions are very similar, what defines them is what makes them different. Lynch syndrome is defined by have a mutation in a MMR gene, whereas family history criteria are used to make a diagnosis of HNPCC.

Lynch syndrome is named after Dr. Henry Lynch, who devoted his career to studying families that had many people affected with cancer. He described families with Lynch syndrome in the 1970s, at a time when people did not think cancer could be inherited since it isn’t something people are born with. His discoveries have led to increased awareness and prevention of many cancers.

City of Hope

Date reviewed: January 8, 2024